Has the drought in Texas ended since several parts of the state received several inches of rain recently? The answer depends on who you ask.
"Trying to determine when a drought has ended is done the same way a fishhook is removed....very carefully," Klaus Wolter, a researcher at the National Oceanic and Atmospheric Administration's Earth System Research Laboratory in Colorado, said in a news relese.
Many factors, including rain, runoff, inflows and social impacts must be considered before determining a drought has ended.
“There isn’t just one specific definition or category of drought,” Travis Miller, Texas AgriLife Extension Service statewide agronomist in College Station, said in the release.
There are four generally acknowledged types of drought—meteorological, hydrological, socioeconomic and agricultural—each as varied as the Texas weather.
Meteorological drought refers to a precipitation deficit in a specific region over a specific time interval compared with historic averages for that same period.
Hydrological drought refers to the effect of reduced precipitation on surface and subsurface water supplies.
Socioeconomic drought occurs when reduced precipitation causes an adverse affect on a region's economy.
And agricultural drought causes dry stock ponds, bare fields and little or no green-up in pastures during a typically lush time of year, Miller said.
“The agricultural economy in drought-stricken areas of the state [of Texas] is impacted because it’s either too dry to plant crops or the crops are withering, and ranchers are feeding livestock hay or other supplementation when they would normally have green grass and full water tanks,” he says.
Although Texas' current agricultural drought has hit farmers' and ranchers pocketbooks for almost $1 billion in losses, most people know the meteorological drought because of news and weather reports.
Meteorological drought is typically categorized using the Palmer Drought Severity Index, which reflects both precipitation and other hydrological conditions. The newer Standardized Precipitation Index reflects differences in precipitation only during specific time scales.
The standardized index is used by the National Drought Mitigation Center because it makes it possible to identify emerging droughts months sooner than with the Palmer index, says Mark Lenz, a meteorologist with the Austin/San Antonio National Weather Service office in New Braunfels, Texaas.
Drought, defined by the U.S. Drought Monitor, is assigned one of five levels or stages—abnormally dry, moderate, severe, extreme or exceptional.
“Even after the rains in late March, each of the 33 Texas counties which this office serves are still either in extreme or exceptional drought,” he said in the news release. “People are often under the impression that after a couple of days of good rains a drought has broken, but that only happens if precipitation over a period of months puts us near the long-term average.”
Lenz says south-central Texas needs 10-15 inches of rain during the next several months to put it back on track and proclaim an end to the drought.
For more information on the Texas drought, visit the Drought Joint Information Center.